The present invention relates to an improved disc-type source holder for radioactive foils used as an ion source and to an assembly of said holder and a radioactive foil.
By way of background, source holders are used to mount a radioactive foil in devices such as ionization chamber smoke detectors. Insofar as pertinent here, in the past disc-type source holders were used which had a precisely sized circular opening therein and which utilized various types of brackets to retain a radioactive foil in position against the disc so that it would radiate through the opening. Holders of this prior art type were deficient in that a relatively complex assembly operation was required to mount a foil on a holder. The same was true of other prior art types of disc holders which were riveted together to provide a sandwich type of arrangement with a foil positioned therebetween.